Conventional Aerial Delivery Systems
Ann Suter, Wildland Fire Chemical Systems - MTDC
Conventional tanks divide the retardant load into several compartments. The compartments can be released individually or
multiple compartments can be released simultaneously to increase both the volume and the flow rate and hence the coverage
level. Multiple compartments can also be released sequentially at the appropriate release interval to increase the volume while
maintaining the coverage level of a single compartment release. Conventional tanks often use deployable flow restrictors to help
control the flow rate. Restrictors are physical barriers that lower the flow rate as liquid is released from the tank. There are a
variety of conventional tanks with different shapes, compartments and capacities. Having the option of restricting the flow
doubles the number of flow rates available to the system
Conventional Tank
Each Compartment holds 250 gallons.
2200
2000
gallons per second
1800
1600
1400
1200
1000
800
2 compartments with restrictors = 430 gallons/second
600
400
200
1 comparment with restrictors = 215 gallons/second
0
0.0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
Time
The figure to the left above shows two compartments released simultaneously with restrictors down. Each compartment flows at
about an average of 215 gallons per second. The dotted line shows the flow rate for one compartment while the solid line shows
the flow rate for two.
Conventional Tank
Each Compartment holds 250 gallons.
2200
2 compartments unrestricted = 1370 gallons/second
2000
gallons per second
1800
1600
1400
1200
1 comparment unrestricted = 685 gallons/second
1000
800
600
400
200
0
0.0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
Time
The figures above illustrate the same thing but without the restrictors deployed. Each compartment flows about an average of
685 gallons per second.
Revision Date 2/6/03
asuter@fs.fed.us 406-329-4815